Duran CS (Chemically strengthened)
Finish state
EN ISO 3585
Use for thin sections and complex shapes needing strength without the optical distortion of thermal toughening; shallow compression layer is lost by deep scratching or reheating.
Values for the CS condition
Other Duran tempers and conditions
Duran is listed in 3 conditions; see the grade overview at Duran.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Standard low-stress annealed Duran for laboratory glassware, tubing, sight glasses and flameworked assemblies. | — | 35 | 0 | 580 HV | 1 W/m·K |
Thermally toughened | Pick when mechanical strength, impact and pressure resistance matter (viewing panels, boiler/oven sight glass); cannot be cut or drilled after toughening. | — | 100 | 0 | 580 HV | 1 W/m·K |
CSThis page Chemically strengthened | Use for thin sections and complex shapes needing strength without the optical distortion of thermal toughening; shallow compression layer is lost by deep scratching or reheating. | — | 120 | 0 | 600 HV | 1 W/m·K |
What is Duran CS?
Duran CS is Duran supplied in the CS condition — use for thin sections and complex shapes needing strength without the optical distortion of thermal toughening; shallow compression layer is lost by deep scratching or reheating. Duran CS has a tensile strength of 120 MPa (17.4 ksi), stronger than 83% of glass grades. Elongation at break is 0% and the elastic modulus is 64 GPa (9.28 Msi). Duran CS has a density of 2.23 g/cm³ (0.0806 lb/in³), lighter than 85% of glass grades. ANN is the default condition FabDigit quotes; CS is available on request or by drawing note.
Advantages
- Lightweight — 2.23 g/cm³ (0.0806 lb/in³), better than 85% of glass grades
- Low embodied carbon — 1.8 kg CO₂/kg, better than 85% of glass grades
Limitations
- Difficult to machine — 4/100, worse than 95% of glass grades
Duran CS properties
Typical room-temperature values for Duran CS; 13 are specific to this condition. Other listed values are Duran reference data and may not represent this condition. Bars are the position among glass grades.
Physical4
Duran CS has a density of 2.23 g/cm³ (0.0806 lb/in³), lighter than 85% of glass grades.
Mechanical12
Duran CS has a tensile strength of 120 MPa (17.4 ksi), stronger than 83% of glass grades. Elongation at break is 0% and the elastic modulus is 64 GPa (9.28 Msi).
Thermal5
Duran CS is rated for continuous service to 350°C (662 °F). It conducts heat at 1.2 W/m·K (0.693 BTU/hr·ft·°F), worse than 58% of glass grades. Thermal expansion is 3.3 µm/m·K (1.83 µin/in·°F).
Electrical5
Duran CS is an electrical insulator with a dielectric strength of 25 kV/mm (635 V/mil) and a resistivity of 1×10¹³ Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (90/100), better than 73% of glass grades.
Sustainability4
Producing a kilogram of Duran CS takes about 27 MJ of energy and emits 1.8 kg of CO₂ — less than 84% of glass grades. Typical recycled content is 8%.
Manufacturability2
Duran CS's machinability is not recommended (4/100, worse than 95% of glass grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Duran CS
Is Duran easy to machine?
No conventional cutting — score-and-break, diamond core drilling, diamond wheel grinding, abrasive waterjet or laser/CNC glass machining, always followed by edge seaming and annealing.
Can Duran be welded?
Flameworked/fusion-joined with oxy-propane or oxy-hydrogen at ~1200 °C; freely sealable to other 3.3 borosilicates (Pyrex 7740, Borofloat 33, Simax) and to tungsten/Kovar-type graded seals.
Can Duran be formed, bent or molded?
Formed by tube drawing, blowing or press-forming near the working point (~1260 °C); every formed part must be annealed around 560 °C to remove residual stress.
What surface finishes work on Duran?
Fire polishing or acid (HF/H2SO4) polishing for optical clarity; frosting/etching with HF, screen-printed ceramic or PTFE coatings for markings — no plating or anodizing.
Duran chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| B2O3gives low CTE 3.3 | 12 – 13.5 | 13 |
| Na2Oalkali, with K2O total ~4 % | 3 – 4.5 | 3.5 |
| K2O | 0 – 1 | 0.5 |
| Al2O3improves chemical durability | 2 – 2.5 | 2 |
| SiO2network former | ≥ 80 (balance) | — |
Duran CS — frequently asked
What is Duran CS used for?
Duran CS is typically used for laboratory glassware, process piping, ampoules and sight glasses. In short: standard borosilicate 3.3 glass; low thermal expansion; interchangeable with Pyrex 7740.
What is the tensile strength of Duran CS?
Duran CS has a typical tensile strength of 120 MPa (17.4 ksi) — stronger than 83% of glass grades. Strength varies by condition: see the 3 listed tempers.
Is Duran CS easy to machine?
Not especially — machinability is rated not recommended (4/100, worse than 95% of glass grades). No conventional cutting — score-and-break, diamond core drilling, diamond wheel grinding, abrasive waterjet or laser/CNC glass machining, always followed by edge seaming and annealing.
Can Duran CS be welded?
Flameworked/fusion-joined with oxy-propane or oxy-hydrogen at ~1200 °C; freely sealable to other 3.3 borosilicates (Pyrex 7740, Borofloat 33, Simax) and to tungsten/Kovar-type graded seals.
What surface finishes work on Duran CS?
Fire polishing or acid (HF/H2SO4) polishing for optical clarity; frosting/etching with HF, screen-printed ceramic or PTFE coatings for markings — no plating or anodizing.
Can Duran CS be formed, bent or molded?
Formed by tube drawing, blowing or press-forming near the working point (~1260 °C); every formed part must be annealed around 560 °C to remove residual stress.
What is the maximum service temperature of Duran CS?
Duran CS is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- DIN ISO 3585 — Borosilicate glass 3.3, properties — DIN/ISO (1999)
- DURAN / BOROFLOAT 33 borosilicate glass technical data — SCHOTT AG (2023)
- ASM Engineered Materials Handbook Vol. 4: Ceramics and Glasses — ASM International (1991)
- ISO 695 / ISO 719 / ISO 720 / DIN 12116 chemical durability test classes — ISO / DIN (2020)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.